Tkinter Hello, World!

Summary: in this tutorial, you’ll learn step by step how to develop the Tkinter “Hello, World!” program.

Creating a window

The following program shows how to display a window on the screen:  

import tkinter as tk root = tk.Tk() root.mainloop()

If you execute the program, you’ll see the following window:

How it works.

First, import the tkinter module as tk to the program:  

import tkinter as tk

Second, create an instance of the tk.Tk class that will create the application window:  

root = tk.Tk()

By convention, the main window in Tkinter is called root. But you can use any other name like main.

Third, call the mainloop() method of the main window object:  

root.mainloop()

The mainloop() keeps the window visible on the screen. If you don’t call the mainloop() method, the window will display and disappear immediately. It will be so fast that you may not see its appearance.

Also, the mainloop() method keeps the window displaying and running until you close it.

Typically, you place the call to the mainloop() method as the last statement in a Tkinter program, after creating the widgets.

Displaying a label

Now, it’s time to place a component on the window. In Tkinter, components are called widgets.

The following adds a label widget to the root window:  

import tkinter as tk


root = tk.Tk()

# place a label on the root window
message = tk.Label(root, text="Hello, World!")
message.pack()

# keep the window displaying
root.mainloop()

Note that you’ll learn more about the Label widget in the upcoming tutorial.

If you run the program, you’ll see the following output:

How it works.

To create a widget that belongs to a container, you use the following syntax:  

widget = WidgetName(container, **options)

Code language: Python (python)

In this syntax:

• The container is the parent window or frame that you want to place the widget.
• The options is one or more keyword arguments that specify the configurations of the widget.

In the program, the following creates a Label widget placed on the root window:  

message = tk.Label(root, text="Hello, World!")

And the following statement positions the Label on the main window:  

message.pack()

Code language: Python (python)

Note that you’ll learn more about the pack() method later. If you don’t call the pack() method, the Tkinter still creates the widget. However, the widget is invisible.

Fixing the blur UI on Windows

If you find the text and UI are blurry on Windows, you can use the ctypes Python library to fix it.

First import the ctypes module:  

from ctypes import windll

Second, call the SetProcessDpiAwareness() function:  

windll.shcore.SetProcessDpiAwareness(1)

If you want the application to run across platforms such as Windows, macOS, and Linux, you can place the above code in a try...finally block:  

try:
    from ctypes import windll

    windll.shcore.SetProcessDpiAwareness(1)
finally:
    root.mainloop()

Summary

• Import tkinter module to create a Tkinter desktop application.
• Use Tk class to create the main window and call the mainloop() method to keep the window displays.
• In Tkinter, components are called widgets.